As recent improvement in standard of living has led to growing demand for a pleasant life, acoustic design for buildings becomes important. Currently, sound-proofing panels having sound absorption capability so as to absorb a variety of interior noise are used as interior materials for buildings. Moreover, a variety of sound absorption sheets and sound absorption panels including the sound absorption sheets are used in fields that require a sound-proofing function, such as interior and exterior materials for car seats.
A sound absorption sheet generally requires permeability and sound absorption capability in order to minimize noise, and requires excellent permeability in order to maximize sound absorption effects. Thus, the sound absorption sheet requires a number of perforations to block noise.
Korean Patent No. 10-0753960 discloses a multilayer sheet for interior materials of vehicles with excellent strength and sound absorption/heat insulating capabilities, which includes a matrix formed by mixing thermoplastic resin fibers and natural fibers, and is fabricated using a conveyer belt composed of a number of perforated plates to form perforations. However, this patent does not describe any improved function of the multilayer sheet formed with pores.